Potatoes are among the most profitable agricultural crops in arable farming in the Netherlands and consequently are grown as frequently as conditions allow. As a result Dutch farmers experienced huge problems with potato cyst nematodes during the last 50 years. In Chapter 1 an outline is presented of the situation of potato cyst nematode control in the 1980's, the problems, possible solutions and the research initiated, of which a part is presented in this thesis.In 1984 emphasis was put into research concerning the efficiency of soil fumigation on heavy marine clay soils where the majority of Dutch seed and consumption potatoes are grown. Both laboratory and field experiments were carried out to investigate the efficiency of 1,3 dichloropropene and metam-natrium. This required the processing of thousands of larvae suspensions. One of the most labourious and tedious occupations in nematological research is the counting of individuals of the pathogen.In Chapter 2 A GOP-302 image analysis system - Context Vision, Sweden - was used to automate the counting of large numbers of larvae-suspensions of Globodera rostochiensis and G. pallida . These suspensions originated from hatching tests, which were conducted to estimate percentage mortality in field and lab experiments of nematodes exposed to nematicides. The result is called ANECS ( A utomatic NE matode C ounting S ystem), a software program that can count up to 64 compartments with larvae suspensions successively without the aid of an operator. A special object carrier was developed. Images of up to eight object carriers (512 larvae suspensions) can be stored and image analysis can be suspended to off-office hours. The time needed to count one compartment was reduced by 80% to one minute compared to 'manual' labour while the time for probe preparation remained the same. The percentile error is highest at very low larvae densities (<20 per suspension) and is caused by pollution with small fibres carried by air during the handling of the larvae suspensions. This ...